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resources caching json asp.net c#

3

orip · 技术社区 · 16 年前

部署后,我想更改一些字符串,而无需重新启动进程(因此.config文件已丢失)。

可以编写高效解析配置文件(XML/JSON/YAML/?)的代码,例如将结果缓存X秒或监视其变化 FileSystemWatcher

Json.NET CacheDependency

public class CachingJsonParser
{
    public static CachingJsonParser Create()
    {
        return new CachingJsonParser(
            HttpContext.Current.Server,
            HttpContext.Current.Cache);
    }

    private readonly HttpServerUtility _server;
    private readonly Cache _cache;

    public CachingJsonParser(HttpServerUtility server, Cache cache)
    {
        _server = server;
        _cache = cache;
    }

    public T Parse<T>(string relativePath)
    {
        var cacheKey = "cached_json_file:" + relativePath;
        if (_cache[cacheKey] == null)
        {
            var mappedPath = _server.MapPath(relativePath);
            var json = File.ReadAllText(mappedPath);
            var result = JavaScriptConvert.DeserializeObject(json, typeof(T));
            _cache.Insert(cacheKey, result, new CacheDependency(mappedPath));
        }
        return (T)_cache[cacheKey];
    }
}

{
    "UserName": "foo",
    "Password": "qwerty"
}

对应数据类:

class LoginData
{
    public string UserName { get; set; }
    public string Password { get; set; }
}

解析和缓存:

var parser = CachingJsonParser.Create();
var data = parser.Parse<LoginData>("~/App_Data/login_data.json");

1 回复 | 直到 16 年前

1

5

Rashmi Pandit 16 年前

CacheDependency : CacheItemUpdateCallback :

编辑: 这是我的示例代码

protected void Page_Load(object sender, EventArgs e)
{
        XmlDocument permissionsDoc = null;

        if (Cache["Permissions"] == null)
        {
            string path = Server.MapPath("~/XML/Permissions.xml");
            permissionsDoc = new XmlDocument();
            permissionsDoc.Load(Server.MapPath("~/XML/Permissions.xml"));
            Cache.Add("Permissions", permissionsDoc,
                            new CacheDependency(Server.MapPath("~/XML/Permissions.xml")),
                           Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration,
                    CacheItemPriority.Default, new CacheItemRemovedCallback(ReloadPermissionsCallBack));
        }
        else
        {
            permissionsDoc = (XmlDocument)Cache["Permissions"];
        }
}

private void ReloadPermissionsCallBack(string key, object value, CacheItemRemovedReason reason)
    {
        XmlDocument doc = new XmlDocument();
        doc.Load(Server.MapPath("~/XML/Permissions.xml"));
        Cache.Insert("Permissions", doc ,
                            new CacheDependency(Server.MapPath("~/XML/Permissions.xml")),
                           Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration,
                    CacheItemPriority.Default, new CacheItemRemovedCallback(ReloadPermissionsCallBack));
    }